The invention relates to a method and apparatus for automatically cutting sheet metal into patterns for forming ductwork, etc. Conventionally, such pattern cutting of sheet metal is done by hand, and is very labor intensive, relatively slow, and requires a large number of skilled laborers to achieve acceptable large volume production. While systems are known for cutting sheet material in general into patterns, such systems really have not been adapted so that they could function in cutting sheet metal of a wide variety of gauges and widths as is necessary when pattern cutting sheet metal for making ductwork, etc.
A number of prior art devices made by Gerber Garment Technology, Inc., such as shown in U.S. Pat. Nos. 3,477,322, 3,370,634, 3,776,074, 3,790,154, and 3,841,187, among others, are successful in cutting patterns in sheet material such as cloth, paper, and the like, however, the cutting means employed by such devices do not, it is believed, provide for easy adaptation to cutting of sheet metal, and large production thereby is usually based on cutting a large stack of sheets all at the same time--not practical with sheet metal--rather than by automatic conveyance of the sheet material into a cutting position.
According to the present invention, automatic pattern cutting of sheet material is practical; something that heretofore has not been practical. According to the present invention a metal sheet is automatically conveyed by conveying means into a pattern cutting position, guidance thereof being provided, and the metal sheet is then automatically clamped into place at the pattern cutting position. A cutting means, which preferably comprises a shear cutter, has one blade thereof being adapted to be disposed above the horizontally disposed metal sheet, and the other blade thereof being adapted to be disposed below the horizontally disposed metal sheet. Supporting means associated with the conveying means support the metal sheet in proper position to allow positioning of the lower blade below the metal sheet for cooperation with the upper blade, and such supporting means prevent damage to the conveying means during the pattern cutting operation. The pattern cutting is controlled by a computer which activates means for moving the cutting means to any x-y coordinate of the horizontal metal sheet, and activates a motor for moving the cutting blades to any angular, .alpha., position.
The cutting means cuts into the metal sheet through a free edge thereof, and cuts any desired pattern. A ball bearing can be provided associated with the lower blade member to allow more exact control of the angular position of the cutting means (especially when right angles or tight curves must be cut). After cutting of the desired pattern from the metal sheet, the clamping means are automatically released, the conveying means started, and the sheet moved away from the pattern cutting position. The sheet may be passed over a roller and the pattern held on the roller while the waste cuttings fall into a waste bin disposed below the roller.
Notching of the metal sheet being pattern cut can also be effected automatically, notches often being necessary at predetermined locations along the edges of a pattern to allow for folding of the sheet to form ductwork, etc. Notching is effected by a notching assembly movable along each side edge of the metal sheet, the notching assemblies receiving the sheet between top and bottom plates thereof. The notching assemblies are controlled by the computer also, as is an indexer for each for bringing a selected one of a plurality of notching dies into operative relationship with the notching punch. The notching assemblies are movable with respect to each other in the direction perpendicular to the feed direction of the metal sheets to accommodate sheets of different widths, and shims may be provided therewith to accommodate sheets of different gauge.
It is the primary object of the present invention to provide a method and apparatus for effecting the automatic pattern cutting of sheet metal. This and other objects of the invention will become clear from an inspection of the detailed description of the invention, and from the appended claims.